Integrated electrical shield in a heat sink

ABSTRACT

A system having a heat exchanger with a bottom side, a first nonconductive layer coupled to the bottom side of the heat exchanger, a heat shield made of an electrically conductive material and being coupled to the first nonconductive layer, and an electrical connector electrically coupled to the heat shield, the electrical connector being capable of being connected to an electrical ground.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to systems for providing heat dissipation andelectrical shielding to integrated circuits.

2. Description of the Known Art

It is well known that integrated circuits emit significant amounts ofheat. It is also known that these integrated circuits can only toleratea certain amount of heat before failing to operate properly. Thisproblem has become more pronounced as a number of transistors packagedwithin a given area of the integrated circuit continue to rise. Toovercome this problem, numerous systems have been devised for removingheat from the integrated circuit. These systems include a variety ofdifferent heat exchangers, the most popular being a finned heat sink.More advanced cooling systems have combined finned heat sinks withelectrical fans, liquid cooling systems and thermoelectric devices.

Another known problem is the amount of electromagnetic radiation emittedby the integrated circuit. The electromagnetic radiation emitted by oneintegrated circuit may affect the operation of other nearby integratedcircuits. Although it is true that some integrated circuits emitrelatively small amounts of electromagnetic radiation, other integratedcircuits, such as class D amplifiers, emit significant amounts ofelectromagnetic radiation. One way of minimizing the effects ofelectromagnetic radiation is to place the integrated circuitsresponsible for emitting significant amounts of electromagneticradiation at a safe distance from other electrical circuits, such thatany radiation generated will have little to no effect. Other ways ofminimizing the emission of electromagnetic radiation include the use ofelectrical shields. These shields, although effective, are relativelylarge compared to the size of the integrated circuit. This problem isexacerbated because many integrated circuits require the use of a heatsink, further increasing the area required to be shielded by theelectrical shield.

D class amplifiers, such as those used in audio systems, are especiallytroublesome because they generate significant amounts of heat as well assignificant amounts of electromagnetic radiation. D class amplifiersamplify an incoming audio signal and output the audio signal in anamplified form. By so doing, the amplified audio signal is capable ofdriving one or more audio speakers. Current home audio systems attach aheat sink to the D class amplifier. A large shield is also placed aroundthe D class amplifier and the attached heat sink to minimize theemission of electromagnetic radiation. This solution, while acceptablein home audio systems, is difficult to implement in automobiles becauseof the relatively small area dedicated to audio electronics.Additionally, as automobile audio systems become more powerful, D classamplifiers emitting even more heat and more electromagnetic radiationmust be implemented.

BRIEF SUMMARY OF THE INVENTION

In overcoming the drawbacks and other limitations of the related art,the present invention provides a system for providing heat dissipationand electrical shielding to integrated circuits. The system includes aheat exchanger with a bottom side, a first nonconductive layer coupledto the bottom side of the exchanger sink and a heat shield made of anelectrically conductive material coupled to the first nonconductivelayer. An electrical connector is electrically coupled to the heatshield and capable of being connected to an electrical ground therebygrounding the heat shield. The grounded heat shield shields othercomponents from emitted electromagnetic radiation and the heat exchangerdissipates heat generated by the integrated circuit.

Further objects, features and advantages of this invention will becomereadily apparent to persons skilled in the art after a review of thefollowing description, with reference to the drawings and claims thatare appended to and form a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an audio electronic system having asystem for providing heat dissipation and electrical shielding embodyingthe principles of the present invention; and

FIG. 2 is a partial cross sectional view generally taken along lines 2-2in FIG. 1 of the system for providing heat dissipation and electricalshielding.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, an audio electronic system 10 is shown. The audioelectronic system 10 includes at least one circuit board 12 populated bya variety of electronic components. More specifically, the circuit board12 is populated by a system for providing electrical shielding and heatdissipation 14 a. Of course, it should be understood that more than onesystem for providing electrical shielding and heat dissipation maypopulate the circuit board 12, as shown by systems 14 b, 14 c. Althoughit was previously mentioned that the system 14 a is utilized in theaudio electronic system 10, it should also be understood that the system14 a may be used in a variety of different applications including, butnot limited to, personal computer circuit boards and computer networkingequipment, such as high speed routers.

Referring to FIG. 2, a cross section of the system for providingelectrical shielding and heat dissipation 14 a, generally taking alonglines 2-2 of FIG. 1, is shown. The system 14 a includes a heat exchanger16 having an exterior side 18 and an interior side 20. The heatexchanger 16 is generally a heat sink, wherein the exterior side 18 ofthe heat sink is formed to define a plurality of fins 22, 24, 26, 28. Inorder to maximize cooling, the heat exchanger 16 is generally made of amaterial that has a high thermal conductivity. Generally, the heatexchanger 16 is made of aluminum. Additional devices to aid the heatexchanger 16 may be coupled to the heat exchanger 16. These additionaldevices may include an electrical fan, a liquid cooling system and/or athermoelectric cooling system.

Coupled to the interior side 20 of the heat exchanger 16 is a firstelectrically nonconductive layer 30. The first nonconductive layer 30may be made out of any electrically nonconductive material, such as anonconductive polymer. Coupled to the first nonconductive layer 30 is aheat shield 32. The heat shield 32 is made of an electrically conductivematerial and is electrically insulated from the heat exchanger 16 by thefirst nonconductive layer 30. The first non conductive layer 30 may bemade of polyimide or epoxy with glass beads. The heat shield 32 isgenerally made of a conductive material including, but not limited to,copper, aluminum, sink, and combinations thereof.

Coupled to heat shield 32, opposite the first nonconductive layer 30, isan integrated circuit 34. The integrated circuit 34 is generally class Damplifier, but may also be any integrated circuit that outputssignificant amounts of electrical noise, such as a power switchingdevice. Optionally, a second nonconductive layer 36 may be locatedbetween the integrated circuit 34 and the heat shield 32, therebyelectrically isolating the integrated circuit 34 from the heat shield32. The second non conductive layer 36 may be made of polyimide or epoxywith glass beads. Heat generated by the integrated circuit 34 willtravel to the heat exchanger 16 via the first and second nonconductivelayers 30, 36 and the heat shield 32.

The integrated circuit 34 is populated on the surface the circuit board12. The circuit board 12 includes at least one ground plane 38, which isconnected to an electrical ground. The ground plane 38 is connected tothe heat shield 32 by a conductive electrical connector 40. When theheat shield 32 is electrically coupled to the ground plane 38 via theelectrical connector 40, the heat shield 32 acts as electrical shield,shielding other components from any electromagnetic radiation generatedby the integrated circuit 34. It should also be understood that althoughthe heat shield 32 is electrically isolated from the heat exchanger 16,the heat shield 32 in thermal communication with the heat exchanger 16as well as the integrated circuit 34. By so doing, heat generated by theintegrated circuit 34 travels through the heat shield 32 to the heatexchanger 16, so as to remove heat from the integrated circuit 34.

As a person skilled in the art will readily appreciate, the abovedescription is meant as an illustration of implementation of theprinciples this invention. This description is not intended to limit thescope or application of this invention in that the invention issusceptible to modification, variation and change, without departingfrom the spirit of this invention, as defined in the following claims.

1. A system for providing electrical shielding and heat dissipation, thesystem comprising: a heat exchanger, the heat exchanger having aninterior side and an exterior side; a first electrically nonconductivelayer coupled to the interior side of the heat exchanger; a heat shieldmade of an electrically conductive material, the heat shield beingcoupled to the first electrically nonconductive layer, opposite the heatexchanger, the first electrically nonconductive layer electricallyisolating the heat shield from the heat exchanger; an electricalconnector electrically coupled to the heat shield, the electricalconnector being connected to an electrical ground; an integrated circuitmounted on a circuit board, the integrated circuit having a top surfacebeing in thermal contact with the heat shield; wherein the circuit boardhas a surface that generally defines a first plane substantiallyparallel to a second plane generally defined by the top surface of theintegrated circuit, the top surface having generally opposed side edges;and wherein the heat shield extends beyond the side edges of the topsurface of the integrated circuit.
 2. The system of claim 1, wherein theintegrated circuit is a class D amplifier.
 3. The system of claim 1,wherein the integrated circuit is a power switching device.
 4. Thesystem of claim 1, further comprising a second electricallynonconductive layer, the second electrically nonconductive layer beinglocated between the integrated circuit and the heat shield.
 5. Thesystem of claim 4, wherein the second electrically nonconductive layeris made of a nonconductive polymer.
 6. The system of claim 1, whereinthe electrical connector electrically connects the heat shield to aground plane of the circuit board.
 7. The system of claim 1, furthercomprising a circuit board having a ground plane, the ground plane ofthe circuit board being electrically connected to the electricalconnector.
 8. The system of claim 1, wherein the heat shield is made ofat least one of copper, aluminum, zinc and combinations thereof.
 9. Thesystem of claim 1, wherein the heat exchanger is a heat sink.
 10. Thesystem of claim 1, wherein the top side of the heat sink defines aplurality of fins.
 11. The system of claim 1, wherein the first nonconductive layer is made of a nonconductive polymer.